Battle of Xu Province (197)

The Battle of Xu Province occurred in 197 AD when Yuan Shu sent an army of 200,000 troops under Zhang Xun to invade Xu Province, the domain of his former ally Lu Bu. The invasion was ordered by Yuan Shu to punish Lu Bu for reneging on a planned marriage alliance with him (and for sending the envoy Han Yin to Cao Cao to be executed).

Background
In 197 AD, the imperial pretender Yuan Shu planned to destroy the Governor of Xu Province, Liu Bei, who had been misled by Cao Cao into attacking Yuan Shu's lands, ostensibly on the Emperor's orders. Yuan Shu was advised by his general Ji Ling to form a marriage alliance with Lu Bu in order to win the mighty warrior's support in defeating Liu Bei, and Lu Bu enthusiastically agreed, preparing to send his daughter Lu Lingqi to Shouchun to marry Yuan Yin. However, Chen Gui advised Lu Bu that Yuan Shu had plans to usurp the title of Emperor, thus making Lu Bu a rebel if he supported him. Lu Bu ultimately withdrew the marriage convoy and imprisoned the envoy Han Yin, claiming that he had to prepare his daughter for the wedding before she could be sent. Cao Cao used this rift to his advantage, having Emperor Xian of Han make Lu Bu a general of the Han dynasty to secure his loyalty. When another messenger from Yuan Shu told Lu Bu that his daughter was to become Empress once Yuan Shu's son took the throne, Lu Bu's suspicions about Yuan Shu were confirmed, and he had the messenger put to death and Han Yin sent to Cao Cao at Xuchang, where he was put to death. This angered Yuan Shu, who prepared a massive army of 200,000 troops under Zhang Xun for an invasion of Lu Bu's base of Xu Province.

Campaign
Yuan Shu's army of 200,000 troops was divided into seven divisions under Zhang Xun, Qiao Rui, Lei Bo, Han Xian, Chen Ji, Chen Lan, and Yang Feng; Ji Ling commanded the reserves, while Yuan Shu himself, Li Deng, Liang Gang, and Yue Jiu coordinated the march with 30,000 troops. Lu Bu's strategist Chen Gong advised him to behead his advisors Chen Deng and Chen Gui for ruining the marriage alliance plans, as this would surely please Yuan Shu. However, Lu Bu promised to spare Chen Deng if he could help him defeat Yuan Shu's army, and Chen Deng convinced him that he could be able to convince the former Han loyalists Han Xian and Yang Feng to defect, while they could also call on Liu Bei for assistance. Chen Deng succeeded in convincing the two generals to eventually defect, and Lu Bu then planned to attack Yuan Shu.

Battles
Lu Bu divided his army into five divisions of 10,000 troops each; Gao Shun led a division to Xiaopei to fight Qiao Rui, Chen Gong faced Chen Ji at Yidu, Zhang Liao and Zang Ba met Lei Bo at Langye, Song Xian and Wei Xu met Chen Lan at Jieshi, and Lu Bu himself would attack Zhang Xun while leaving a small guard at Xuzhou. Han Xian and Yang Feng's troops let Lu Bu's army into Zhang Xun's camp, and Zhang Xun was routed by the surprise attack. At daylight, Lu Bu and Ji Ling's armies met in battle, and Yang Feng and Han Xiang also attacked, forcing Ji Ling to flee. Yuan Shu then ambushed Lu Bu's force as he gave chase, and Lu Bu wounded Li Deng in a duel before routing Yuan Shu's force. Guan Yu and his army of Liu Bei's troops then blocked Yuan Shu's retreat, and his army was massacred until it fled across the Huai River. Lu Bu then held banquets and feasts in honor of his five generals, the two defectors, and Guan Yu, and Guan Yu returned to Yu Province after the victory, while Han Xian was made Governor of Yidu and Yang Feng Governor of Langye.

Aftermath
The defeated Yuan Shu returned to Jiangdong and sent a request for reinforcements to Sun Ce, his protege, but Sun Ce said that he would rather punish a renegade such as Yuan Shu rather than help him. Cao Cao then sent a messenger to Sun Ce and appointed him Governor of Kuaiji before ordering him to march on Yuan Shu. Cao Cao, Sun Ce, Liu Bei, and Lu Bu then agreed to form a coalition against Yuan Shu, and Cao Cao brought 170,000 troops with him. Liu Bei presented Cao Cao with the heads of Yang Feng and Han Xian, who had been executed for allowing their soldiers to plunder the people. Cao Cao then conferred upon Lu Bu a general's rank and promised him an official seal as soon as he returned to the capital, winning Lu Bu's support. The coalition army then began the Siege of Shouchun.